KR102503730B1 - Display device and driving method of the same - Google Patents

Abstract

The display device includes a display panel including pixels, and a light emitting control unit that outputs a light emitting control signal for controlling light emission timing of the pixels, wherein luminance displayed on the pixels is defined as a first luminance period and a second luminance period. , The first time interval between the rising edge of the light emission control signal and the rising edge of the vertical sync signal representing the start of the frame period is adjusted in the first luminance period, and the falling edge of the light emission control signal in the second luminance period. A second time interval between and a rising edge of the vertical synchronization signal may be adjusted.

Description

Display device and display device driving method {DISPLAY DEVICE AND DRIVING METHOD OF THE SAME}

The present invention relates to a display device having improved display characteristics and a method for driving the display device.

An organic light emitting display device includes a light emitting element, and the light emitting element can generate light by recombination of electrons and holes. The organic light emitting diode display has a fast response speed and is driven with low power consumption. However, when a moving image is displayed on the organic light emitting display device, an afterimage of the image may remain, causing the outline of the object to become blurred or indistinct. In order to prevent this phenomenon, an impulse driving method has been developed in which an image is displayed only for a part of a frame and black is displayed for the rest of the time.

An object of the present invention is to provide a display device and a display device driving method with improved display characteristics by controlling a driving method according to each luminance range.

A display device according to an exemplary embodiment of the present invention includes a display panel that displays an image and includes pixels, and a light emission control unit that outputs light emission control signals for controlling light emission timing of the pixels in a frame period. The displayed luminance is defined as a first luminance section and a second luminance section different from the first luminance section, and in the first luminance section, the rising edge of the light emission control signal and the rising edge of the vertical synchronization signal indicating the start of the frame section. A first time interval between edges may be adjusted, and a second time interval between a falling edge of the emission control signal and a rising edge of the vertical synchronization signal in the second luminance period may be adjusted.

A third time interval between the falling edge of the light emitting control signal and the rising edge of the vertical sync signal in the first luminance period is fixed, and the rising edge of the light emitting control signal and the vertical sync signal in the second luminance period. The fourth time interval between the rising edges of ? may be fixed.

The first luminance section may have lower luminance than the second luminance section.

A third luminance section having higher luminance than the second luminance section is further defined, and a time interval between a rising edge of the light emitting control signal and a rising edge of the vertical synchronization signal and a falling edge of the light emitting control signal in the third luminance period. A time interval between and a rising edge of the vertical synchronization signal may be fixed.

An off duty ratio of the emission control signal in the third luminance period may be greater than or equal to 10%.

As the luminance decreases in the first luminance period, an off duty ratio of the emission control signal may increase.

As the luminance decreases in the second luminance period, an off duty ratio of the emission control signal may increase.

As the luminance increases in the second luminance period, an off duty ratio of the emission control signal may increase.

A third time interval between the falling edge of the emission control signal and the rising edge of the vertical synchronization signal in the first luminance interval is adjusted, and the third time interval decreases as the luminance decreases in the first luminance interval. can

A third luminance section, which is an intermediate luminance section between the first luminance section and the second luminance section, is further defined, and a time between a rising edge of the emission control signal and a rising edge of the vertical sync signal in the third luminance section is defined. Both an interval and a time interval between a falling edge of the emission control signal and a rising edge of the vertical synchronization signal may be adjusted.

A display device according to an exemplary embodiment of the present invention displays an image, includes a display panel including pixels, and a light emitting control unit outputting a light emitting control signal having an on level for emitting light of the pixels and an off level for not emitting light of the pixels. The luminance displayed by the pixel is defined as a first luminance range and a second luminance range higher in luminance than the first luminance range, and in the first luminance range, the front end of the off level of the emission control signal is defined as and, in the second luminance period, a rear end of the off level of the emission control signal may be adjusted.

A rear end of the off level of the light emission control signal in the first luminance period and a front end of the off level of the light emission control signal in the second luminance period may be fixed.

As the luminance decreases in the first luminance period, an off duty ratio of the emission control signal may increase.

As the luminance decreases in the second luminance period, an off duty ratio of the emission control signal may increase.

As the luminance increases in the second luminance period, an off duty ratio of the emission control signal may increase.

A rear end of the off level of the emission control signal may be adjusted in the first luminance period.

A method of driving a display device according to an exemplary embodiment of the present invention includes providing a scan signal to a scan line electrically connected to a pixel including a pixel circuit and a light emitting device, and a data signal transferred to a data line by the scan signal. The step of transmitting the light emission control signal to the pixel circuit, the step of adjusting the duty ratio of the light emission control signal according to the luminance displayed on the pixel, and applying the light emission control signal to the pixel circuit to control the timing at which the driving current flows through the light emitting element. In the step of adjusting the duty ratio, when the luminance is in the first luminance range, the front end of the off level of the emission control signal is adjusted, and the luminance is higher than that of the first luminance range. In the case of the second luminance period including the second luminance period, the tail end of the off level of the emission control signal may be adjusted.

In the step of adjusting the duty ratio, the time interval between the rising edge of the light emitting control signal and the rising edge of the vertical sync signal representing the start of the frame period in the first luminance period is adjusted, and the falling edge of the light emitting control signal and A time interval between rising edges of the vertical sync signal is fixed, a time interval between a rising edge of the light emitting control signal and a rising edge of the vertical sync signal in the second luminance period is fixed, and the light emitting control signal A time interval between the falling edge of and the rising edge of the vertical synchronization signal may be adjusted.

An off duty ratio of the emission control signal may increase as the luminance decreases in the first luminance period and the second luminance period.

The off duty ratio of the emission control signal may increase as the luminance decreases in the first luminance section and the second luminance section, and the off duty ratio of the emission control signal may increase as the luminance increases in the second luminance section. there is.

According to an embodiment of the present invention, in the first luminance section, which is a low luminance section, the first stage of the off level of the emission control signal is controlled to improve the first frame response level, and in the second luminance section, which is a high luminance section, the emission control signal's An afterimage phenomenon in which traces of a previous image remain even after an image is changed to another image can be improved by controlling the back end of the off-level.

1 is a perspective view of a display device according to an exemplary embodiment of the present invention.
2 is a block diagram of a display device according to an exemplary embodiment of the present invention.
3 is an equivalent circuit diagram of a pixel according to an embodiment of the present invention.
FIG. 4 illustratively illustrates a vertical sync signal, a light emission control signal, and scan signals applied to the pixels of FIG. 3 .
5 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.
6 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.
7 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.
8 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.
9 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.
10 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification, when an element (or region, layer, section, etc.) is referred to as being “on,” “connected to,” or “coupled to” another element, it is directly connected/connected to the other element. It means that they can be combined or a third component can be placed between them.

Like reference numerals designate like components. Also, in the drawings, the thickness, ratio, and dimensions of components are exaggerated for effective description of technical content. “And/or” includes any combination of one or more that the associated elements may define.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In addition, terms such as "below", "lower side", "above", and "upper side" are used to describe the relationship between components shown in the drawings. The above terms are relative concepts and will be described based on the directions shown in the drawings.

The terms "include" or "have" are intended to indicate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but that one or more other features, numbers, or steps are present. However, it should be understood that it does not preclude the possibility of existence or addition of operations, components, parts, or combinations thereof.

1 is a perspective view of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1 , the display device DD may display the image IM through the display surface IS. The display surface IS is an outermost surface of the display device DD and may be a surface viewed by a user.

1 illustrates a clock display window and application icons as an example of the image IM. In FIG. 1 , it is illustrated that the display surface IS has a surface defined by a first direction DR1 and a second direction DR2 crossing the first direction DR1 . However, in another embodiment of the present invention, the display surface (not shown) of the display device (not shown) may have a curved shape.

The third direction DR3 indicates the normal direction of the display surface IS, that is, the thickness direction of the display device DD. Directions indicated by the first to third directions DR1 , DR2 , and DR3 are relative concepts and may be converted into other directions. Hereinafter, the same reference numerals refer to directions indicated by the first to third directions DR1 , DR2 , and DR3 , respectively.

1 illustrates that the display device DD is a portable electronic device. However, the display device (DD) includes large electronic devices such as televisions, monitors, or external billboards, as well as small and medium-sized electronic devices such as personal computers, notebook computers, personal digital terminals, car navigation units, game consoles, smartphones, tablets, and cameras. It can also be used for devices and the like. In addition, these are merely presented as examples, and can be employed in other electronic devices without departing from the concept of the present invention, of course.

The display surface IS includes a display area DA0 where the image IM is displayed and a non-display area NDA0 adjacent to the display area DA0. The non-display area NDA0 is an area in which an image is not displayed. The display area DA0 may have a standard shape such as a square or a circle, or may have an irregular shape. The non-display area NDA0 may surround the display area DA0. However, it is not limited thereto, and the shape of the display area DA0 and the shape of the non-display area NDA0 may be designed relatively. For example, the display surface IS may not include the non-display area NDA0.

2 is a block diagram of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2 , the display device DD may include a display panel 100 and a driving circuit 200 . The driving circuit 200 is a circuit for driving the display panel 100 and may include a signal controller 210 , a gate driver 220 , a data driver 230 , and an emission controller 240 .

The display panel 100 may be an organic light emitting display panel. The display panel 100 may include a plurality of data lines DL1 to DLm, a plurality of scan lines GL1 to GLn, a plurality of emission control lines EL1 to ELn, and a plurality of pixels PX. can

The plurality of scan lines GL1 -GLn and the plurality of emission control lines EL1 -ELn extend in the first direction DR1 and along the second direction DR2 crossing the first direction DR1. Arranged, the plurality of data lines DL1 to DLm extend in the second direction DR2 and may be arranged along the first direction DR1. The plurality of data lines DL1 to DLm, the plurality of emission control lines EL1 to ELn, and the plurality of scan lines GL1 to GLn define pixel areas, and pixels displaying images in the pixel areas. PXs may be provided. 1 illustrates a pixel PX connected to the first data line DL1 , the first scan line GL1 , and the first emission control line EL1 as an example.

The pixel PX may display one of primary colors or one of mixed colors. The main color may include red, green, blue, and white, and the mixed color may include various colors such as yellow, cyan, and magenta. However, the color displayed by the pixel PX is not limited thereto.

The signal controller 210 (or timing controller) may receive a control signal CS and image data RGB provided from the outside. The signal controller 210 provides the first control signal CONT1 and the image data signal R`G`B` to the data driver 230 and provides the second control signal CONT2 to the gate driver 220. and outputs the third control signal CONT3 to the light emitting controller 240 .

The first control signal CONT1 is a signal for driving the data driver 230, the second control signal CONT2 is a signal for controlling the gate driver 220, and the third control signal CONT3 is a light emitting controller. This is a signal for controlling 240.

The data driver 230 may drive the plurality of data lines DL1 -DLm in response to the first control signal CONT1 received from the signal controller 210 . The data driver 230 may be implemented as an independent integrated circuit and electrically connected to one side of the display panel 100 or directly mounted on the display panel 100 . Also, the data driver 230 may be implemented as a single chip or may include a plurality of chips.

The gate driver 220 drives the scan lines GL1 - GLn in response to the second control signal CONT2 from the signal controller 210 . The gate driver 220 may be integrated in a predetermined area of the display panel 100 . In this case, the gate driver 220 may be implemented as a circuit using an amorphous silicon gate (ASG) using an amorphous silicon thin film transistor (a-Si TFT), an oxide semiconductor, a crystalline semiconductor, a polycrystalline semiconductor, or the like. there is. In addition, the gate driver 220 may be implemented as an independent integrated circuit chip and electrically connected to one side of the display panel 100 . In another embodiment, the gate driver 220 may be implemented as a tape carrier package (TCP) or a chip on film (COF).

The emission controller 240 drives the emission control lines EL1 - ELn in response to the third control signal CONT3 from the signal controller 210 . The light emitting controller 240 may be integrated with the gate driver 220 or provided separately. The light emitting controller 240 may be integrated in a predetermined area of the display panel 100 or may be implemented as an independent integrated circuit chip and electrically connected to one side of the display panel 100 .

While a gate-on voltage is applied to one of the plurality of scan lines GL1 -GLn, a switching transistor of each of pixels in one row connected to the gate-on voltage is turned on. At this time, the data driver 230 provides data driving signals corresponding to the image data signals R'G'B' to the data lines DL1-DLm. The data driving signals supplied to the data lines DL1 to DLm are applied to the corresponding pixel PX through the turned-on switching transistor. The light emitting control unit 240 may apply a light emitting control signal to one of the light emitting control lines EL1 to ELn to determine a timing at which a driving current flows to the light emitting device (OLED, see FIG. 3 ).

3 is an equivalent circuit diagram of a pixel according to an exemplary embodiment of the present invention, and FIG. 4 illustratively illustrates a vertical sync signal, a light emission control signal, and a scan signal applied to the pixel of FIG. 3 . In FIG. 3 , one pixel PXx is illustrated as an example.

Referring to FIG. 3 , the pixel PXx may include a pixel circuit CC and a light emitting device OLED.

The light emitting device OLED may include an organic light emitting diode. However, it is not limited thereto, and depending on the type of the display panel 100 (see FIG. 2), the light emitting device OLED may include an inorganic light emitting diode or an organic-inorganic hybrid light emitting diode.

The pixel circuit CC may include a plurality of transistors T1 to T7 and a storage capacitor Cst. The plurality of transistors T1 to T7 include a driving transistor T1, a switching transistor T2, a compensation transistor T3, an initialization transistor T4, a first light emission control transistor T5, and a second light emission control transistor T6. ), and a bypass transistor T7.

The pixel PXx has a first scan line 14 that transfers the x-th scan signal SSx to the switching transistor T2 and the compensation transistor T3, and an x−1 th scan signal SSx- to the initialization transistor T4. 1), the third scan line 34 for transmitting the x+1th scan signal SSx+1 to the bypass transistor T7, and the first light emission control transistor T5. and the emission control line 15 transmitting the emission control signal ESx to the second emission control transistor T6, the data line 16 transmitting the data signal DSy, and the power line transmitting the power supply voltage ELVDD. 26, and an initialization line 22 for transmitting an initialization voltage Vint for initializing the driving transistor T1.

The gate electrode G1 of the driving transistor T1 is connected to the first electrode C1 of the storage capacitor Cst. The source electrode S1 of the driving transistor T1 is connected to the power line 26 via the first emission control transistor T5. The drain electrode D1 of the driving transistor T1 is electrically connected to the anode of the light emitting element OLED via the second emission control transistor T6. The driving transistor T1 receives the data signal DSy according to the switching operation of the switching transistor T2 and supplies the driving current Id to the light emitting element OLED.

The gate electrode G2 of the switching transistor T2 is connected to the first scan line 14 . The source electrode S2 of the switching transistor T2 is connected to the data line 16 . The drain electrode D2 of the switching transistor T2 is connected to the source electrode S1 of the driving transistor T1 and connected to the power line 26 via the first emission control transistor T5. The switching transistor T2 is turned on according to the x-th scan signal SSx transmitted through the first scan line 14 and transmits the data signal DSy transmitted to the data line 16 as a source of the driving transistor T1. A switching operation is performed to transfer to the electrode S1. For example, the switching transistor T2 may be turned on when the x-th scan signal SSx is at a low level. At this time, the storage capacitor Cst stores a voltage corresponding to the data signal DSy.

The gate electrode G3 of the compensation transistor T3 is connected to the first scan line 14 . The source electrode S3 of the compensation transistor T3 is connected to the drain electrode D1 of the driving transistor T1 and connected to the anode of the light emitting element OLED via the second light emission control transistor T6. The drain electrode D3 of the compensation transistor T3 is connected to the first electrode C1 of the storage capacitor Cst, the source electrode S4 of the initialization transistor T4, and the gate electrode G1 of the driving transistor T1. has been The compensation transistor T3 is turned on according to the x-th scan signal SSx transmitted through the first scan line 14 and connects the gate electrode G1 and the drain electrode D1 of the driving transistor T1 to each other. The driving transistor T1 is diode connected.

The gate electrode G4 of the initialization transistor T4 is connected to the second scan line 24 . The drain electrode D4 of the initialization transistor T4 is connected to the initialization line 22 . The source electrode S4 of the initialization transistor T4 is connected to the first electrode C1 of the storage capacitor Cst, the drain electrode D3 of the compensation transistor T3, and the gate electrode G1 of the driving transistor T1. do. The initialization transistor T4 is turned on according to the x-1th scan signal SSx-1 transmitted through the second scan line 24 to apply the initialization voltage Vint to the gate electrode G1 of the driving transistor T1. is transmitted to initialize the voltage of the gate electrode G1 of the driving transistor T1. For example, the initialization transistor T4 may be turned on when the x−1 th scan signal SSx−1 is at a low level.

The gate electrode G5 of the first light emission control transistor T5 is connected to the light emission control line 15 . The first emission control transistor T5 may be connected between the power line 26 and the driving transistor T1. The source electrode S5 of the first emission control transistor T5 is connected to the power supply line 26 . The drain electrode D5 of the first emission control transistor T5 is connected to the source electrode S1 of the driving transistor T1 and the drain electrode D2 of the switching transistor T2. As the emission control signal ESx is applied to the gate electrode G5 of the first emission control transistor T5, the first emission control transistor T5 is turned on and the driving current Id flows through the light emitting element OLED. . The first light emission control transistor T5 may determine the timing at which the driving current Id flows through the light emitting element OLED.

The gate electrode G6 of the second light emission control transistor T6 is connected to the light emission control line 15 . The second light emission control transistor T6 may be connected between the driving transistor T1 and the light emitting element OLED. The source electrode S6 of the second emission control transistor T6 is connected to the drain electrode D1 of the driving transistor T1 and the source electrode S3 of the compensation transistor T3. The drain electrode D6 of the second light emission control transistor T6 is electrically connected to the anode of the light emitting element OLED. The first light emission control transistor T5 and the second light emission control transistor T6 are turned on according to the light emission control signal ESx transmitted through the light emission control line 15 . As the emission control signal ESx is applied to the gate electrode G6 of the second emission control transistor T6, the second emission control transistor T6 is turned on and the driving current Id flows through the light emitting element OLED. . The second light emission control transistor T6 may determine the timing at which the driving current Id flows through the light emitting element OLED.

The emission control signal ESx may include an on level and an off level. In an embodiment of the present invention, the on level may be when the emission control signal ESx is at a low level, and the off level may be when the emission control signal ESx is at a high level. When the light emission control signal ESx is at a high level, the first light emission control transistor T5 and the second light emission control transistor T6 are turned off. When the first emission control transistor T5 is turned off, the power line 26 and the source electrode S1 of the driving transistor T1 are electrically blocked. Accordingly, the light emitting element OLED may not emit light while the high level emission control signal ESx is provided.

The gate electrode G7 of the bypass transistor T7 is connected to the third scan line 34 . The source electrode S7 of the bypass transistor T7 is connected to the anode of the light emitting element OLED. The drain electrode D7 of the bypass transistor T7 is connected to the initialization line 22 . The bypass transistor T7 is turned on according to the x+1 th scan signal SSx+1 transmitted through the third scan line 34 to initialize the anode of the light emitting element OLED.

The second electrode C2 of the storage capacitor Cst is connected to the power line 26 . The first electrode C1 of the storage capacitor Cst is connected to the gate electrode G1 of the driving transistor T1, the drain electrode D3 of the compensation transistor T3, and the source electrode S4 of the initialization transistor T4. do.

A cathode of the light emitting element OLED receives the reference voltage ELVSS. The light emitting element OLED receives the driving current Id from the driving transistor T1 and emits light.

When the emission control signal ESx has an on level, that is, a low level, the first emission control transistor T5 and the second emission control transistor T6 are turned on. When the first emission control transistor T5 is turned on, the power supply voltage ELVDD is applied to the source electrode S1 of the driving transistor T1. When the second light emission control transistor T6 is turned on, the drain electrode D1 of the driving transistor T1 and the anode electrode of the light emitting element OLED are electrically connected. Then, the light emitting element OLED generates light having a predetermined luminance in response to the received amount of driving current Id.

In another embodiment of the present invention, the number and connection relationship of the plurality of transistors T1 to T7 and the storage capacitor Cst constituting the pixel PXx may be variously changed.

5 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention.

Referring to FIG. 5 , the vertical synchronization signal Vsyn may be a signal indicating the start of one frame. The first to sixth light emission control signals ESa1 to ESa6 may be light emission control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESa1 to ESa3 are some of light emission control signals when the luminance displayed on the pixel PXx is within the first luminance range BS1, and the fourth to sixth light emission control signals ESa4 - ESa6 show some of emission control signals when the luminance displayed on the pixel PXx is within the second luminance range BS2 .

The first luminance period BS1 may be a lower luminance period than the second luminance period BS2. For example, the first luminance period BS1 may be a period having a luminance of 2 nits or more and less than 100 nits, and the second luminance period BS2 may be a period having a luminance of 100 nits or more and 750 nits or less. However, this is exemplary and the luminance boundary between the first luminance section BS1 and the second luminance section BS2 may be changed in various ways.

In the first luminance period BS1 , the luminance of the pixel PXx may be controlled by controlling the off duty ratio of the first to third emission control signals ESa1 to ESa3 . The off duty ratio may be a ratio occupied by a high level within one cycle of the emission control signal. In this embodiment, the high level is referred to as an off duty ratio because it corresponds to an off period in which pixels are not turned on.

In the second luminance period BS2, the luminance of the pixel PXx is controlled by controlling the data signal DSy (refer to FIG. 3) as well as the off duty ratio of the fourth to sixth emission control signals ESa4 to ESa6. can

5 , the first luminance of the pixel PXx may be the lowest when the first emission control signal ESa1 is provided to the pixel PXx, and the pixel PXx may have the lowest luminance when the sixth emission control signal ESa6 is provided to the pixel PXx. ) may have the highest second luminance. That is, when the second to fifth light emission control signals ESa2 to ESa5 are provided to the pixel PXx, the pixel PXx may sequentially display a luminance between the first luminance and the second luminance. .

The off duty ratio of the first light emission control signal ESa1 may be the largest, and the off duty ratio of the sixth light emission control signal ESa6 may be the smallest. For example, if luminance of 2 nit is displayed by the first emission control signal ESa1, the off duty ratio of the first emission control signal ESa1 may be 98%. In each of the first luminance period BS1 and the second luminance period BS2, the off duty ratio may be controlled according to the luminance.

Each of the first to sixth emission control signals ESa1 to ESa6 may include a rising edge and a falling edge. The rising edge indicates a transition from a low level to a high level of each of the first to sixth light emission control signals ESa1 to ESa6, and a falling edge indicates a transition between the first to sixth light emission control signals ESa1 to ESa6 ) may mean a transition from a high level to a low level.

In the first luminance period BS1, the front end FOL1 of the off level of the first to third emission control signals ESa1 to ESa3 may be adjusted. In this embodiment, since the off level is the high level, the off duty can be adjusted by adjusting the length of the front end FOL1 of the high level. Also, in this embodiment, the rear end BOL1 of the off level of the first to third emission control signals ESa1 to ESa3 may be fixed.

A time interval between the rising edge REv of the vertical synchronization signal Vsyn and the front end FOL1 of the off level of the first to third emission control signals ESa1 to ESa3 may be adjusted.

The rising edge REv of the vertical synchronization signal Vsyn and the rising edge REa1 of the first emission control signal ESa1 have a first time interval t1, and the rising edge REv of the vertical synchronization signal Vsyn and the rising edge REa2 of the second light emission control signal ESa2 has a second time interval t2, and the rising edge REv of the vertical synchronization signal Vsyn and the rising edge of the third light emission control signal ESa3 (REa3) may have a third time interval t3. The first time interval t1, the second time interval t2, and the third time interval t3 may be different from each other. However, the falling edges FE of the first to third emission control signals ESa1 to ESa3 are fixed. Accordingly, the rising edge REv of the vertical synchronization signal Vsyn and the falling edge FE of the first to third emission control signals ESa1 to ESa3 may have a fixed time interval tf1.

In the second luminance period BS2, the rear end BOL2 of the off level of the fourth to sixth light emission control signals ESa4 to ESa6 may be adjusted. In this embodiment, since the off level is the high level, the off duty can be adjusted by adjusting the length of the rear end BOL2 of the high level. Also, in this embodiment, the first end FOL2 of the off level of the fourth to sixth light emission control signals ESa4 to ESa6 may be fixed.

A time interval between the rising edge REv of the vertical synchronization signal Vsyn and the rear end BOL2 of the off level of the fourth to sixth light emission control signals ESa4 to ESa6 may be adjusted.

The rising edge REv of the vertical synchronization signal Vsyn and the falling edge FEa4 of the fourth light emission control signal ESa4 have a fourth time interval t4, and the rising edge REv of the vertical synchronization signal Vsyn and the falling edge FEa5 of the fifth light emission control signal ESa5 has a fifth time interval t5, and the rising edge REv of the vertical synchronization signal Vsyn and the falling edge of the sixth light emission control signal ESa6 (FEa6) may have a sixth time interval (t6). The fourth time interval t4, the fifth time interval t5, and the sixth time interval t6 may be different from each other. However, the rising edges RE of the fourth to sixth light emission control signals ESa4 to ESa6 are fixed. Accordingly, the rising edge REv of the vertical synchronization signal Vsyn and the rising edge RE of the fourth to sixth emission control signals ESa4 to ESa6 may have a fixed time interval tf2.

According to an embodiment of the present invention, in controlling the off duty of the emission control signal, the front end or the rear end of the off level is selectively adjusted according to the luminance range. Therefore, in the second luminance section BS2, which is a high luminance section, since the off-level of the emission control signal is controlled at the latter end, the afterimage phenomenon in which traces of the previous image remain even after the image is changed to another image can be improved. Also, in the first luminance period BS1, which is a low luminance period, the first frame response level can be improved because the front end of the off level of the emission control signal is controlled. For example, unlike the embodiment of the present invention, when the latter stage of the off level is controlled even in the first luminance period BS1, the interval Tx between the data input period td and the first on period after the start of the frame is the luminance As the value decreases, it may gradually become farther away. As the interval Tx widens, a sufficient amount of current may not be delivered to the light emitting element (OLED, see FIG. 3), especially at low luminance, and as a result, image quality deterioration such as color change may occur. However, according to an embodiment of the present invention, the front stage of the off level is controlled below a predetermined luminance range. Accordingly, the interval Tx between the data input period td and the first on-period of the light emission control signal after the start of the frame is fixed, so that the image quality deterioration can be prevented.

6 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention. In describing FIG. 6 , components similar to those described in FIG. 5 are briefly mentioned, and descriptions thereof are omitted.

Referring to FIG. 6 , first to ninth light emission control signals ESb1 to ESb9 are illustrated. The first to ninth light emission control signals ESb1 to ESb9 may be light emission control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESb1 to ESb3 are some of light emission control signals when the luminance displayed in the pixel PXx is within the first luminance range BS1a, and the fourth to sixth light emission control signals ESb4 to ESb6 show some of light emission control signals when the luminance displayed on the pixel PXx is within the second luminance range BS2a, and the seventh to ninth light emission control signals ESb7 to ESb9 ) shows some of the emission control signals when the luminance displayed on the pixel PXx is within the third luminance range BS3a.

The first luminance period BS1a may be a period having lower luminance than the second luminance period BS2a, and the third luminance period BS3a may be a period having higher luminance than the second luminance period BS2a. For example, the third luminance section BS3a may be a luminance section of 100 nits or more.

In the first luminance period BS1a, the first to third light emission control signals ESb1 to ESb3 are the same as the first to third light emission control signals ESa1 to ESa3 (see FIG. 5) described in FIG. 5, The front end (FOLa) of the off level can be adjusted. Therefore, since the interval Tx between the data input period td and the first on-period of the light emission control signal after the start of the frame is fixed, deterioration in picture quality can be prevented.

In the second luminance period BS2a, the fourth to sixth light emission control signals ESb4 to ESb6 are the same as the fourth to sixth light emission control signals ESa4 to ESa6 described in FIG. 5 (see FIG. 5). , the back end of the off level (BOLa) can be adjusted. Accordingly, an afterimage phenomenon in which traces of a previous image remain may be improved.

Duty ratios of the seventh to ninth light emission control signals ESb7 to ESb9 in the third luminance period BS3a may be fixed. Accordingly, the time interval tfa between the rising edge RE of the seventh to ninth light emission control signals ESb7 to ESb9 and the rising edge REv of the vertical synchronization signal Vsyn and the seventh to ninth light emission control A time interval tfb between the falling edge FE of the signals ESb7 to ESb9 and the rising edge REv of the vertical synchronization signal Vsyn may be fixed.

In the third luminance period BS3a, the luminance of the pixel PXx may be controlled by adjusting only the data signal DSy (see FIG. 3). The off duty of the seventh to ninth light emission control signals ESb7 to ESb9 of the third luminance period BS3 may be 10% or more. This may be an example of a numerical value in which an afterimage phenomenon in which a trace of a previous image remains is not found. Accordingly, the off duty of the seventh to ninth light emission control signals ESb7 to ESb9 may be changed according to the size, type, and driving voltage condition of the display panel 100 (see FIG. 2 ).

7 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention. In describing FIG. 7 , components similar to those described in FIG. 5 are briefly mentioned, and descriptions thereof are omitted.

Referring to FIG. 7 , first to sixth emission control signals ESc1 to ESc6 are illustrated. The first to sixth light emission control signals ESc1 - ESc6 may be light emission control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESc1 to ESc3 are some of light emission control signals when the luminance displayed in the pixel PXx is within the first luminance range BS1b, and the fourth to sixth light emission control signals ESc4 - ESc6 show some of the emission control signals when the luminance displayed on the pixel PXx is within the second luminance range BS2b.

In the first luminance period BS1b, the first to third light emission control signals ESc1 to ESc3 are the same as the first to third light emission control signals ESa1 to ESa3 (see FIG. 5) described in FIG. 5, The front end (FOLb) of the off level can be adjusted. Accordingly, the interval Tx between the data input period td and the first on-period of the light emission control signal after the start of the frame is fixed, so that the image quality deterioration can be prevented.

In the first luminance period BS1b, the luminance may be controlled by adjusting the off duty ratio of the first to third emission control signals ESc1 to ESc3. That is, as the luminance decreases in the first luminance period BS1b, the off duty ratio of the emission control signal may increase. Accordingly, the off duty ratio of the first light emission control signal ESc1 having the lowest luminance may be the largest among the first to third light emission control signals ESc1 - ESc3 .

In the second luminance period BS2b, the off duty ratio may be adjusted by adjusting the rear end BOLb of the off level of the fourth to sixth emission control signals ESc4 to ESc6. In the second luminance period BS2b, the off duty ratio of the emission control signal may increase as the luminance increases. That is, in the embodiment of the present invention, the afterimage phenomenon in which traces of the previous image remain is controlled only by adjusting the off duty ratio of the first to third emission control signals ESc1 to ESc3 in the first luminance period BS1b. The luminance displayed on the pixel PXx (see FIG. 3) may be controlled by adjusting the data signal DSy (see FIG. 3). Accordingly, the afterimage phenomenon in the high luminance section may be improved.

8 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention. In describing FIG. 8 , components similar to the configuration described in FIG. 5 are briefly mentioned, and descriptions thereof are omitted.

Referring to FIG. 8 , first to eighth emission control signals ESd1 to ESc8 are illustrated. The first to eighth light emission control signals ESd1 to ESd8 may be light emission control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESd1 to ESd3 are some of light emission control signals when the luminance displayed on the pixel PXx is in the first luminance range BS1c, and the fourth and fifth light emission control signals ESd4 and ESd5 are some of light emission control signals when the luminance displayed on the pixel PXx is the second luminance range BS2c, and the sixth to eighth light emission control signals ESd6 to ESd8 are the pixel PXx. Some of the emission control signals when the luminance displayed in (PXx) is the third luminance period BS3c are shown.

In the first luminance period BS1c, both the front end FOL1c and the rear end BOL1c of the off level of the first to third emission control signals ESd1 to ESd3 may be adjusted. For example, as the luminance decreases, the front end FOL1c of the off level may increase, and the rear end BOL1c of the off level may become shorter. However, since the off duty ratio should gradually increase as the luminance decreases, the length of the off level may gradually increase. For example, as the luminance decreases, the ratio at which the front end FOL1c is increased may be greater than the ratio at which the rear end BOL1c is shortened. In this case, the interval (Tx) between the data input period (td) and the first on-period of the light emission control signal after the start of the frame can be further reduced, so that deterioration in picture quality can be prevented.

In the second luminance period BS2c, both the front end FOL2c and the rear end BOL2c of the off level of the fourth and fifth emission control signals ESd4 and Esd5 may be adjusted. For example, as the luminance decreases, the front end of the off-level (FOL2c) and the rear end of the off-level (BOL2c) may become longer.

In the third luminance period BS3c, the sixth to eighth light emission control signals ESd6 to ESd8 are the same as the fourth to sixth light emission control signals ESa4 to ESa6 (see FIG. 5) described with reference to FIG. 5. An afterimage phenomenon in which traces of a previous image remain may be improved by adjusting the rear end of the off level (BOL3c). Also, the front end FOL3c of the off level may be fixed.

9 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention. In the description of FIG. 9, components similar to the configuration described in FIG. 8 are briefly mentioned, and descriptions thereof are omitted.

Referring to FIG. 9 , first to sixth emission control signals ESe1 to ESe6 are illustrated. The first to sixth light emitting control signals ESe1 to ESe6 may be light emitting control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESe1 to ESe3 are some of light emission control signals when the luminance displayed in the pixel PXx is within the first luminance range BS1d, and the fourth to sixth light emission control signals ESe4 - ESe6 show some of emission control signals when the luminance displayed on the pixel PXx is within the second luminance range BS2d. The second luminance period BS2d may be a higher luminance period than the first luminance period BS1d.

In the first luminance period BS1d, the first to third light emission control signals ESe1 to ESe3 are the same as the first to third light emission control signals ESd1 to ESd3 (see FIG. 8) described with reference to FIG. 8. Both the front end of the off level (FOL1d) and the end of the off level (BOL1d) can be adjusted.

In the second luminance period BS2d, the fourth to sixth emission control signals ESe4-ESe6 have a predetermined off-duty ratio that can improve the afterimage phenomenon in which traces of the previous image remain. ) can be adjusted. For example, the off duty ratio may be 10% or more. In the second luminance period BS2d, the luminance of the pixel PXx may be controlled by fixing the end of the off level BOL2d and adjusting the data signal DSy (refer to FIG. 3).

10 is a diagram illustrating a vertical synchronization signal, an x-th scan signal, and emission control signals according to luminance according to an embodiment of the present invention. In the description of FIG. 10, components similar to those described in FIGS. 5 and 9 will be briefly mentioned, and descriptions thereof will be omitted.

Referring to FIG. 10 , first to sixth emission control signals ESf1 to ESf6 are illustrated. The first to sixth light emission control signals ESf1 - ESf6 may be light emission control signals provided to the pixel PXx when different luminances are displayed on the pixel PXx (see FIG. 3 ).

The first to third light emission control signals ESf1 to ESf3 are some of light emission control signals when the luminance displayed in the pixel PXx is within the first luminance range BS1e, and the fourth to sixth light emission control signals ESf4 - ESf6 show some of the emission control signals when the luminance displayed on the pixel PXx is within the second luminance range BS2e. The second luminance period BS2e may be a higher luminance period than the first luminance period BS1e.

In the first luminance period BS1e, the first to third light emission control signals ESf1 to ESf3 are the same as the first to third light emission control signals ESa1 to ESa3 (see FIG. 5 ) described in FIG. 5 . The front end FOL1e of the off level can be adjusted. Accordingly, the interval Tx between the data input period td and the first on-period of the emission control signal after the start of the frame is fixed.

In the second luminance period BS2e, the fourth to sixth light emission control signals ESf4 to ESf6 are the same as the fourth to sixth light emission control signals ESe4 to ESe6 (see FIG. 8) described in FIG. 8, The rear end of the off level (BOL2e) may be adjusted to have a predetermined off duty ratio capable of improving the afterimage phenomenon in which traces of the previous image are left, and then fixed.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the art do not deviate from the spirit and technical scope of the present invention described in the claims to be described later. It will be understood that the present invention can be variously modified and changed within the scope not specified. Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims.

DD: display device 100: display panel
200: drive circuit PX: pixel
BS1: first luminance section BS2: second luminance section
ESx: light emission control signal SSx-1: x-1st scanning signal
SSx: x-th scanning signal SSx+1: x+1-th scanning signal

Claims (20)

a display panel that displays an image and includes pixels; and
A light emitting control unit outputting a light emitting control signal for controlling light emitting timing of the pixel in a frame period;
The luminance displayed on the pixel is defined as a first luminance range and a second luminance range different from the first luminance range,
A first time interval between a rising edge of the light emitting control signal and a rising edge of a vertical synchronization signal indicating the start of the frame period in the first luminance period is adjusted so that the front end of the off level of the light emitting control signal is controlled;
The display device of claim 1 , wherein a second time interval between a falling edge of the emission control signal and a rising edge of the vertical synchronization signal is adjusted in the second luminance period to control the off level of the emission control signal. According to claim 1,
A third time interval between the falling edge of the emission control signal and the rising edge of the vertical sync signal in the first luminance period is fixed;
A fourth time interval between a rising edge of the emission control signal and a rising edge of the vertical synchronization signal in the second luminance period is fixed. According to claim 1,
The first luminance range has a lower luminance than the second luminance range. According to claim 3,
A third luminance section having higher luminance than the second luminance section is further defined,
The time interval between the rising edge of the light emission control signal and the rising edge of the vertical sync signal and the time interval between the falling edge of the light emission control signal and the rising edge of the vertical sync signal in the third luminance period are fixed. . According to claim 4,
The off duty ratio of the emission control signal in the third luminance period is 10% or more. According to claim 1,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance decreases in the first luminance period. According to claim 1,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance decreases in the second luminance period. According to claim 1,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance increases in the second luminance period. According to claim 1,
A third time interval between the falling edge of the emission control signal and the rising edge of the vertical synchronization signal is adjusted in the first luminance interval, and the third time interval decreases as the luminance decreases in the first luminance interval. display device. According to claim 1,
A third luminance section, which is an intermediate luminance section between the first luminance section and the second luminance section, is further defined,
A display in which a time interval between a rising edge of the light emission control signal and a rising edge of the vertical synchronization signal and a time interval between a falling edge of the light emission control signal and a rising edge of the vertical synchronization signal are both adjusted in the third luminance period. Device. a display panel that displays an image and includes pixels; and
A light emitting control unit outputting a light emitting control signal having an on level that causes the pixel to emit light and an off level that causes the pixel to not emit light;
The luminance displayed by the pixel is defined as a first luminance section and a second luminance section higher in luminance than the first luminance section, and in the first luminance section, the front end of the off level of the emission control signal is adjusted. In the second luminance period, the rear end of the off level of the emission control signal is adjusted. According to claim 11,
A rear end of the off level of the emission control signal in the first luminance period and a front end of the off level of the emission control signal in the second luminance period are fixed. According to claim 11,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance decreases in the first luminance period. According to claim 11,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance decreases in the second luminance period. According to claim 11,
The display device of claim 1 , wherein an off duty ratio of the emission control signal increases as the luminance increases in the second luminance period. According to claim 11,
A display device in which a rear end of the off level of the emission control signal is adjusted in the first luminance period. providing a scan signal to a scan line electrically connected to a pixel including a pixel circuit and a light emitting element;
transferring the data signal transmitted to the data line by the scan signal to the pixel circuit;
adjusting a duty ratio of an emission control signal according to the luminance displayed on the pixel; and
Applying the light emitting control signal to the pixel circuit to control a timing at which a driving current flows through the light emitting element;
In the step of adjusting the duty ratio, when the luminance is in the first luminance range, the front end of the off level of the emission control signal is adjusted, and the luminance is in the second luminance range including a higher luminance than the first luminance range. , the rear end of the off level of the emission control signal is adjusted. According to claim 17,
In the step of adjusting the duty ratio,
A time interval between a rising edge of the light emitting control signal and a rising edge of a vertical sync signal representing the start of a frame period in the first luminance period is adjusted, and a falling edge of the light emitting control signal and the rising edge of the vertical sync signal are adjusted. The time interval between is fixed,
The time interval between the rising edge of the light emitting control signal and the rising edge of the vertical sync signal in the second luminance period is fixed, and the time interval between the falling edge of the light emission control signal and the rising edge of the vertical sync signal is fixed. A method of driving the controlled display device. According to claim 17,
and an off duty ratio of the emission control signal increases as the luminance decreases in the first luminance period and the second luminance period. According to claim 17,
wherein the off duty ratio of the light emission control signal increases as the luminance decreases in the first luminance period, and the off duty ratio of the light emission control signal increases as the luminance increases in the second luminance period.

Images